There are generally two kinds of energy storage structures currently available in the market, one that stores energy by using a spring, and the other that stores energy by using a compressed gas. Both the modes have a common characteristic in that during operation, a thrust applied to a piston varies with the position of the piston, i.e., the thrust is maximum at an initial position thereof, and the thrust is minimum at a final position thereof. In other words, the thrust from the above energy storage structure gradually decreases as the stored potential energy is gradually released. Conversely, the thrust from the energy storage structure gradually increases as the stored potential energy is increased during energy storage.
Both the structures have a large contour dimension, and after being shaped, intensity of impact energy each time is invariable, i.e., a constant value.